In head perfusion imaging in an X-ray computed tomography apparatus, blood vessel images of a head are obtained in a time-series in addition to a perfusion image of the head. The user can readily find a collateral circulation caused by angiostenosis or the like by observing the time-series blood vessel images of the head.
There has been a technique of calculating a delay time for each pixel of a portion to be examined using, as a reference time, a time when a contrast agent reaches a specific portion of a brain, and generating an image (to be referred to as a delay image hereinafter) representing the spatial distribution of the delay times (see, for example, patent literature 1). The delay time is defined by, for example, the difference between the earliest time when the blood vessels of the brain start to dye with a contrast agent and the time when the blood vessels of an arbitrary portion of the brain start to dye with the contrast agent.
There is also provided a technique of generating an image (to be referred to as a TTP image hereinafter) which represents the two-dimensional distribution of times (TTPs: time to peak) when a CT value reflecting the existing ratio of a contrast agent in blood vessels becomes largest after the contrast agent flows into a specific portion to be examined.
If time-series blood vessel images of a head are used, it is difficult to find a collateral circulation because it depends on image observation by the user.
The present invention has as its object to provide a medical diagnostic image processing apparatus capable of improving the quality of image diagnosis by the user.